Terrazzo tile



p 1967 M. GOOZNER 3,344,011

TERRAZZO TILE Filed Nov. 2, 1964 f3 T 3 26 INVENTOR ATTORNEYS PatentedSept. 26, 1967 3,344,011 TERRAZZU TILE Murray Goozncr, 642 Diane Place,Valley Stream, N.Y. 11581 Filed Nov. 2, 1964, Ser. No. 408,259 8 Claims.(1. 16144) The present invention relates generally to improvements infacing material and it relates particularly to an ornamentalterrazzo-like tile having a synthetic resin matrix and an improvedmethod of producing the same.

As is well known, terrazzo floors have for many years been made byspreading a mixture of concrete containing marble chip aggregate overthe surface to be covered, allowing the concrete to harden in situ, andthen grinding the protruding portions of the aggregate down to the levelof the hardened concrete and then grinding further to produce a smoothsurface. Such floors are very costly to produce, are obviously notsuitable for economic mass production, and are exceedingly heavy,necessitating increased costs for structural supports, particularly forupper floors. Recent attempts to substitute synthetic resin for theconcrete obviously fall short of constituting a complete solution of theaforementioned problems, and further raise other problems such as thedefective installations resulting from the existence of bubbles, voidsor air holes below or in the floor surfaces.

It is, therefore, a principal object of the present invention to providean improved terrazzo simulating tile and a method of producing the same.

Another object of the present invention is to provide an improvedterrazzo simulating tile having a synthetic organic polymer matrix.

' Still another object of the present invention is to provide a terrazzosimulating tile of a unique and highly ornamental and attractiveappearance.

A further object of the present invention is to provide an improvedornamental terrazzo simulating tile which may be easily and rapidlyinstalled.

Still a further object of the present invention is to provide animproved tile of the above nature characterized by its versatility,adaptability and low cost.

The above and other objects of the present invention will becomeapparent from a reading of the following description taken inconjunction with the accompanying drawing, wherein;

- FIGURE 1 is a top perspective view of a shell section of a tile inaccordance with the present invention;

FIGURE 2 is a sectional view taken along line 22 in FIGURE 1;

FIGURE 3 is a view similar to FIGURE 2 with the shell cavity filled withthe terrazzo forming mass;

FIGURE 4 is a top perspective view of the finished tile;

FIGURE 5 is a sectional View taken along line 5-5 in FIGURE 4; and

FIGURE 6 is an enlarged detailed transverse sectional view of anotherembodiment of the present invention.

' In a sense the present invention contemplates the provision of anornamental tile comprising a shallow opentopped shell member including abottom wall and an upwardly directed peripheral wall, a matrix of asolid synthetic organic polymer disposed in an substantially fillingsaid shell and adhering to the walls thereof and having an upper face,and an aggregate material distributed throughout said matrix and exposedat said matrix upper face. The terrazzo tiles so provided have beenfound to be extremely durable, strong, light in weight, dimensionallystable, resistant to acid, alkali, solvents, fats and oils, steam,microorganisms, etc. economical to manufacture and install, non-porous,resilient, flexible, and having a highly ornamental surface and whichmay assume various shapes, configurations and appearances.

Referring now to the drawings and particularly FIG- URES 1 to 5 thereofwhich illustrate a preferred embodiment of the present invention, thereference numeral 10 generally designates the improved tile member whichcomprises a shallow open-topped shell member 12 and a terrazzosimulating filler 14 adherent to the walls thereof. While the tilemember 10 may be of any desired configuration it is advantageouslysquare and may have dimensions which are conventionally employed infloor tile, for example 9" x 9", 12" X 12", 24" x 24", and of anydesired height, for example about As" to /2 inch or more. The shellmember 12 comprises a fiat bottom wall 16 and a peripheral wall 18 whichmay be integrally formed with the bottom wall 16 or may be separate andcemented or otherwise adhered thereto. The upper face 20 of theperipheral wall 18 is exposed when the tile is used and the wall 18 maythus be formed of any attractive material and the face 20 may besuitably decorated. A highly attractive tile may be produced by formingthe wall 18 of flat wooden strips having abutting bevelled end edges,the width of the wooden strips depending on the desired appearance. Thewall 16 may be formed of any suitable preferably flexible material andmay be a thermoplastic resin or an elast-omeric material.

The filler or core member 14 includes a matrix 22 formed of syntheticorganic polymeric resin, advantageously an epoxy resin, as will behereinafter set forth, and a relatively coarse aggregate 24 distributedtherethrough, particularly adjacent the upper surface of the core member22 and may also include a relatively fine aggregate concentratedprimarily at the lower section of the core member 14. The coarseaggregate 24 is advantageously marble chips having flat exposed upperfaces substantially coplanar with the upper face of the matrix 14 andthe peripheral wall upper face 20. It is important to note that theinner face of the shell 12 adherent to the matrix 14 and forms a unittherewith and the shell 12 and the matrix 14 are formed of materialswherein the matrix, particularly the alkyd resins which when set orpolymerized in the shell 12, firmly adheres to the inner face of theshell 12. The walls 16 and 18 of the shell 10 may be formed of wood,metal, synthetic organic resins, for example polyvinyl chloride, saran,polyethylene, polypropylene, polystyrene, preferably of the high impacttype, nylon, polyesters, etc. The inner faces of the shell wall shouldbe clean of any material which would function as a parting agent such asoils, greases, soft waxes and the like.

The epoxy resins employed as the matrix herein are well-known in the artand no claim is made thereto .per se except in combination with theother materials and procedures here disclosed and claimed for theproduction of a novel terrazzo tile. In general, these epoxy resins maybe described as complex polymeric reaction products of the reaction of amole of a polyhydric phenol with one to two or more :moles of apolyfunctional halohydrin in the presence of an amount of an alkalinematerial at least sufficient, and usually up to 30% in excess, tocombine with or neutralize the halide liberated from the halohydrin.Such products contain terminal epoxy groups and, in some instances,lower amounts of terminal hydroxy groups. The term epoxy group refers toa triatomic heterocycle composed of one oxygen atom and two saturatedcarbon atoms. These epoxy resins operative herein, their compositionsand methods for their production are disclosed in numerous priorpublications including for example U.S. Patents Nos. 2,585,115,2,602,785, etc. The most typical and preferred epoxy resin is producedby the reaction of 2,2-bis(4-hydroxyphenyl)propane, commonly known asbis-phenol, with epichlorhydrin in the presence of an alkali such ascaustic soda.

Instead of or in addition to bis-phenol, other polyhydric phenols may beemployed, particularly dihydric mononuclear phenols such as resorcinol,catechol, hydroquinone, etc., and polynuclear phenols such as4,4'-dihydroxybenzophenone, 1,1 bis(4 hydroxyphenyl)ethane, 1,1- bil(4hydroxyphenyl)isobutane, 2,2 bis(4 hydroxyphenyl)butane, 2,2 bis(4hydroxy 2 methylphenyl) propane, 2,2 bis(4 hydroxynaphthyl)methane, 1,5dihydroxynaphthalene, etc. Instead of or in addition to epichlorhydrin,there may be employed epibromhydrin, epiiodohydrin, beta methylepichlorhydrin, gamma methyl epichlorhydrin, glycerol dichlorhydrin,etc.

' These epoxy resins are marketed by a number of different companiesunder such trademarks as ERL, Epi-Rez, Hysol, Epon, Araldite, Bakelite,etc., and are available in a number of grades, viscosities, and othervariable properties depending upon the particular end use. For use inthe present invention, the epoxy resin should be sufficiently fluid tofill and level off in the shell with a minimum of bubble entrapment,while yet being sutficiently viscous to prevent settlings of theaggregate to the bottom of the shell prior to hardening of the resin.The viscosity may range, for example, from that of a syrup to that of athick paint or pourable wet concrete mix, depending upon the size andamount of aggregate and the speed of hardening, it being necessary thatat least some of the marble chips aggregate protrude above the surfacelevel of the hardened resin matrix for the attainment of the desiredeffect. Any necessary thinning of fiuidization may be accomplished inknown manner by addition to the epoxy resin composition of a fluidizingamount of a normally liquid mono-epoxy reactive diluent or acyano-substituted hydrocarbon. As examples of such mono-epoxy diluents,there may be mentioned as preferred those which boil above 100 C. andare therefore substantially non-volatile, such as the monoglycidylethers including methyl, ethyl, butyl, isopropyl, allyl, crotyl,isoamyl, phenyl, o-tolyl, p-tolyl, thymyl, and naphthyl glycidyl ethers,or the less preferred propylene oxide, isobutylene oxide, butadienemonoxide, 1,2-pentylene oxide, octylene oxide, styrene oxide, glycidol,decylene oxide and the like. Preferred cyano-substituted hydrocarbonsart those containing 2 to 8 carbon atoms and normally liquid,particularly acetonitrile and methyl cyanide. It will be understood thatas employed herein, the term epoxy resin is inclusive of the resincomposition with or without such fluidizing additives, and that the termliquid epoxy resin refers to a resin having the required viscositycharacteristics described above which can be achieved in known manner byworkers skilled in the art.

The marble chip aggregate employed in the present invention may have anydesired particle configuration and size, usually ranging for examplefrom /s" to 1" in diameter or thickness and being of irregular shapes.Similarly, this aggregate may be used in any desired proportions in theresin, as for example from about 0.2 to 10 parts per part of epoxyresin. The size distribution and the proportion of aggregate will ofcourse depend upon the effects desired, the size and thickness of thetile, etc. Generally, higher proportions are more economical in view ofthe relatively high cost of the epoxy resin.

In producing the tiles of the present invention, a hardening agent(otherwise referred to as a curing agent, crosslinking agent, orcatalyst) must be mixed with the epoxy resin and marble chip aggregateto effect hardening of the resin in the shell. A great variety of suchhardening agents are known, such as alkalies like sodium or potassiumhydroxide; alkali phenoxides like sodium phenoxides; carboxylic acids oranhydrides such as formic acid, oxalic acid or phthalic anhydride;Friedel-Crafts metal halides like aluminum chloride, zinc chloride,ferric chloride or boron trifluoride as well as complexes thereof withethers,

acid anhydrides, ketones, diazonium salts, etc. phosphoric acid andpartial esters thereof including n-butyl orthophosphate, diethylorthophosphate and hexaethyl tetraphosphate; and, preferably, aminocompounds such as triethyl amine, ethylene diamine, diethyl amine,di-n-butylamine, diethylene triamine, triethylene tetramine, pyridine,piperidine, dicyandiamide, melamine, and the like. The amounts vary withthe particular agent. For the alkalies or phenoxides, 2% to 4% issuitable. With phosphoric acid and esters thereof, good results areobtained with 1% to 10% added. The amino compounds are used in amountsof about 5% to 15%, and the others involve addition of about 1% to 20%.

Since flexibility, resilience and toughness are desired, and brittlenessor extreme hardness is a disadvantage in handling, installation and use,particularly for fioor tiles, the epoxy resin should be selected forsuch desired properties, being available by reason of proper control ofthe proportions of reactants, reaction conditions, inclusion of knownplasticizers, etc. Such desirable properties can additionally beachieved by use of a hardening agent which also yields these desirableproperties. As such hardening agents with plural functions, there may bementioned the polymeric polyamide reaction products of polymeric fatacids containing at least 2 carboxyl groups with an aliphatic polyaminesuch as ethylene diamine or di ethylene triamine, as discussed in US.Patent Nos. 2,450,940 and 2,705,223, and available on the market as, forexample, Versamid 125, etc. Alternatively or in addition, epoxidizedcashew nut oil (available as Cardolite NC513-3MCO) may be employed as acomponent of the epoxy resin, functioning both as a plasticizer and as afluidizer or viscosity reducer.

The method for producing the novel tiles of the present inventioninvolves filling a shell 12 with liquid epoxy resin containing epoxyhardener and marble chip aggregate protruding above the surface of saidliquid, allowing the epoxy resin to harden, and then grinding theprotruding portions of the marble chip aggregate down to the level ofthe hardened epoxy resin. The shell may have any desired size and shape,as aforesaid, depending upon the product desired. Prior to filling, itis important that the inner surfaces of the shell should be clean of anyparting agents. The epoxy resin, hardening agent therefor, and marblechip aggregate are simply mixed in conventional equipment such as ascrew type mixer, and deposited in the shell 12 in an amount so that theresin is at substantially the level of the shell upper edge. Aspreviously explained, the resin mix must have the proper viscosity tominimize entrapment of bubbles, without permitting settling of suspendedaggregate to the bottom of the shell. The viscosity is of course not soimportant when sufficient particles of aggregate are large enough torest on the bottom of the shell and protrude above the surface level ofthe resin. Conversely, if relatively small size aggregate is used, theviscosity of the resin mix must be high enough, or the rate of hardeningincreased enough as by increasing the amount of hardening agent, orboth, to maintain the desired proportion of aggregate protruding abovethe resin level during hardening, which may not be completed for /2 to 4or more hours.

As a further feature of the invention, the mixture in the mold issubjected to a de-aerating treatment to eliminate or minimize entrapmentof voids or bubbles therein. Preferably, this is accomplished bymechanical vibration, as by vibrating the resin filled shell on avibrating table for 10-15 minutes following the shell-filling operation.Other de-aerating means may be applied simultaneously, consecutively, oralternatively, such as vacuum, heat, and/ or ultrasonic vibrations, etc.A low porosity tile is thus obtained with increased strength anddiminished tendencies toward failure in use.

After the resin has hardened sufliciently to bond firmly with theaggregate and the shell, conventional grinding means are employed togrind the protruding portions of the aggregate down to the surface levelof the hardened resin. Little or no resin need be ground to yield ahighly pleasing and eifective smooth, polished terrazzo surface. Anysurface bubbles remaining can be broken by application of a spray of lowboiling volatile solvent such as acetone or methyl ethyl ketone, or byultrasonic vibrations or the like.

The foregoing method results in a tile which usually has some smallholes or voids in the bottom surface facing the mold bottom. When a lessporous tile is desired, the following method may be employed.

A resin-rich mixture of epoxy resin, hardener, and fine particle sizeaggregate is first deposited into the shell. This fine size aggregate ispreferably sand, although marble dust, silica, barytes, mica, silicates,calcium sulfate, alumina, emery, corundum, diatomaceous earth, burnedclays, ground slag, etc. may be employed. The shell is then vibrated for5 to minutes to settle this fine size aggregate to and adjacent theshell bottom, after which the desired amount of marble chip aggregate issprinkled or spread over the surface of the partially hardened epoxyresin in the shell and the shell again vibrated for about 5 to 10minutes. This second vibrating treatment serves to embed the marble chipaggregate in the upper portion of the tile with many of the particlesprotruding above the surface level of the resin. After the resin hashardened sufiiciently, a grinding treatment and, if necessary, treatmentof the surface to break air bubbles is applied as described above. Thismethod yields a tile of lower porosity and with little or no entrapmentof bubbles or voids as compared with tiles produced by the previouslydescribed method due to the dual vibrating treatment and the use of thefine particle size aggregate for filling the voids adjacent the lowersurface of the tile. In this method, since most of the marble chipaggregate is concentrated in the upper portion of the tile where maximumuse is made of its ornamental and wear-resisting properties, lowerproportions of such aggregate can be employed, as for example about to75% of the amounts used in the previously described method. The fineparticle size aggregate can be employed in even lower proportionsranging for example from about 0.1 to 0.5 parts per part of epoxy resin.

As a further feature of this invention, it has been found that evenfurther improvements can be obtained with respect to appearance,anti-skid and wear-resisting properties by including in the tile apredetermined amount of hardened phenolic resin aggregate, the particlesof which are irregularly shaped and of a size similar to the marble chipaggregate, or smaller if so desired. Any desired amount of hardenedphenolic resin aggregate may be employed although the desired effect cangenerally be obtained by substitution of about 10 to 50% of the marblechip aggregate otherwise used, with the hardened phenolic resinaggregate.

The hardened phenolic resin aggregate is conveniently and economicallyobtained as a by-product of the phenolic plastics industry wherein agreat variety of objects are made by molding phenol-formaldehyde resincompositions (usually containing a small amount of catalyst and largerproportions of inert filler material) in any desired size and shapeconfiguration to a fully cured, hardened condition with or withoutapplication of heat. A great deal of scrap is produced during themolding operation, mainly constituted by the excess resin squeezed outof the molds and known as flashing. Similar amounts of scrap areobtained from broken pieces, rejects, ofi grade lots, and faultycastings. All this scrap presently poses a disposal problem which is atleast partially solved by the use made of such scrap in the productionof the terrazzo tiles of the present invention. This freely availablescrap is readily adapted for use herein by simply reducing the size ofthe scrap particles, as by free roller crushing and screening, toapproximately the size of the marble chip aggregate or smaller. Theresulting particles of hardened phenolic resin are similar to the marblechip aggregate in being irregularly shaped, angular grid particles, andare employed herein by simply adding them together with the marble chipaggregate in the methods described above for producing the tiles of thepresent invention. As with the marble chip aggregate, portions ofhardened phenolic resin aggregate remain protruding above the surfacelevel of the hardened resin matrix in the shell and are ground down tosuch level together with the marble chip aggregate as described. Theresulting surface presents a field of hardened epoxy resin, usuallywhite, ivory or egg-shell in color, interrupted by irregularly shapedinsets of marble, of varying color depending upon the source of themarble chips, and of hardened phenolic resin, usually black though ofany color depending upon the color of the objects from which the scrapwas obtained. It will be understood that the epoxy resin may be coloredby addition of any suitable pigment or dye.

The following examples are only illustrative of certain embodiments ofthis invention and are not to be regarded as limitative. All parts andproportions referred to herein and in the appended claims are by Weightunless otherwise indicated.

Example 1 parts of liquid epoxy resin containing the reaction product ofbis-phenol and epichlorhydrin, 10 parts of diethylene triamine hardener,40 parts of hardened phenolic resin aggregate ranging from about A; to/2" in size, and 60 parts of marble chip aggregate of similar size ismixed in a screw type mixer and deposited into a 9" x 9" shell, theinterior cavity of which has a depth of The filled shell is vibrated ona vibrating table for about 10 minutes, and the resin then allowed toharden for a few hours, after which the protruding portions of hardenedphenolic resin and marb e chip aggregate are ground down and the surfaceof the tile polished smooth.

Example 2 100 parts of liquid epoxy resin as in Example 1, 15 parts ofVersamid polyamide of flexibilizer-hardener, and 20 parts of buildingsand is mixed in a screw type mixer and deposited into a 12" x 12" shellhaving clean faces and a depth of /4". The filled shell is vibrated on avibrating table for about 5 minutes after which a mixture of 20 parts ofhardened phenolic resin aggregate and 30 parts of marble chip aggregatesized as in Example 1 is spread over the surface of the resin. The shellis again vibrated on avibrating table for about 10 minutes, the surfaceof the tile sprayed with acetone, and the resin then allowed to harden.The protruding portions of hardened phenolic resin and marble chipaggregate are then ground down and the tile surface polished smooth.

For certain applications, it has been found useful to eliminate themarble chip aggregate entirely and utilize only phenolic resin as theaggregate, since marble chips, which are essentially limestone, areeasily attacked by inorganic acids, the production of a terrazzo-liketile composition including a hardened epoxy resin matrix and anaggregate of phenolic resin chips.

By employing a 100% phenolic chip aggregate, there is obtained aterrazzo-like tile which is completely resistant to inorganic acids.Such tile is useful in electroplating plants, breweries, dairies or likeplaces where strong acetic conditions are encountered on floors orwalls. Similarly, in laundries, soap manufacturing plants, or otherareas where strong alkaline conditions prevail. The use of tilescontaining the 100% phenolic chip aggregate would be more desirable thantiles containing a mixture of marble chip and phenolic resin chipaggregate.

In FIGURE 6 of the drawing there is illustrated another embodiment ofthe present invention, differing from that first described only in theconstruction of the shell member. The tile member is designated as 26and includes an open topped shell member 28 which may be of any desiredconfiguration and size and of any suitable material as above set forthand includes integrally formed base wall and an upstanding peripheralwall 32. The inner face 34 of the wall 32 is downwardly outwardlyinclined to provide an undercut. The shell cavity is filled with a corecomprising a synthetic organic polymer resin matrix 36, advantageouslyan epoxy resin, having an aggregate 38 distributed therethrough. Theupper faces of the matrix 36, aggregate 38 and peripheral Wall 32 arepreferably substantially coplanar and the peripheral border of the core32 mates the undercut inner face of the peripheral wall 32 to therebyeffect the interlocking of the core and shell. The tile 26 may beproduced in the manner of the tile 10.

While there have been described and illustrated preferred embodiments ofthe present invention, it is apparent that numerous alterations,omissions and additions may be made without departing from the spiritthereof.

What is claimed is:

1. An ornamental tile comprising a shallow open topped shell memberincluding a bottom wall and an upwardly directed peripheral wall, amatrix of a solid synthetic organic polymer disposed in andsubstantially filling said shell and adhering to the walls thereof andhaving an upper face, and an aggregate material distributed throughoutsaid matrix and exposed at said matrix upper face, said peripheral Wallhaving a Width at least several times greater than the height thereofand being made of a material contrasting with said matrix and saidaggregate to provide a composite tile having an ornamental upper surfaceconstituting a central body bordered by a wide, contrasting frame.

2. An ornamental tile comprising a shallow open topped shell memberincluding a bottom wall and an upwardly directed peripheral wall, asolid epoxy resin matrix disposed in and substantially filling saidshell and adhering to the walls thereof and having a substantiallyplanar upper face, and an aggregate material distributed throughout saidmatrix and having exposed upper faces substantially coplanar with theupper face of said matrix, said peripheral wall having an upper surfacesubstantially wider than the height thereof and being made of a materialcontrasting with said matrix and said aggregate, the upper surface ofsaid peripheral wall being substantially coplanar with the upper face ofsaid matrix to provide a unitary tile having an ornamental upper surfaceconstituting a terrazzo-like body bordered by a wide, contrasting frame.

3. The ornamental tile of claim 2 wherein said peripheral wall is madeof wood.

4. The ornamental tile of claim 2 wherein said aggregate comprisesgranules of a solid phenolic resin.

5. An ornamental tile comprising a rectangular shallow open topped shellmember having a rectangular bottom wall and a shallow upstandingperipheral wall, a solid epoxy resin matrix filling said shell andadherent to the walls thereof and having a fiat upper face substantiallycoplanar with the upper edge of said peripheral Wall, and an aggregatedistributed throughout said matrix and having flat upper facessubstantially coplanar with the upper face of said matrix, saidperipheral wall formed of wooden strips of greater width than height.

6. The ornamental tile of claim 5 wherein the inner face of saidperipheral wall is inclined downwardly and cutwardly, providing anundercut mating with the margin of said matrix to lock the latter tosaid shell.

7. The improved method of producing an ornamental tile comprising thesteps of providing a shallow shell having a central cavity bordered by arectangular peripheral wall of substantially greater width than heightand having a Wide flat upper surface and resin adherent inner faces,filling the central cavity of said shell with a liquid epoxy resincontaining an epoxy hardener and an aggregate protruding above thesurface of said liquid, allowing the epoxy resin to harden and adhere tothe walls of said shell and then grinding the protruding portions of theaggregate and the upper surface of the hardened epoxy resin, down to thelevel of the upper surface of said peripheral wall, to provide a unitarytile having a flat ornamental upper surface constituting a central bodybordered by a wide frame.

8. The improved method of producing an ornamental tile comprising thesteps of providing a shallow shell having a central cavity bordered by arectangular peripheral wall of substantially greater width than heightand having a wide flat upper surface and resin adherent inner faces,filling the central cavity of said shell with a liquid epoxy resincontaining an epoxy hardener and an aggregate of relatively smallparticle size, vibrating said shell to settle said aggregate adjacent tothe lower surface of the shell, spreading marble chips aggregate ofrelatively larger particle size in the surface of said liquid, againvibrating the shell to embed said marble chip aggregate partially andcompletely in the surface of said liquid, allowing the epoxy resin toharden and adhere to the walls of the shell, and then grinding theprotruding portion of the marble chip aggregate and the upper surface ofthe hardened epoxy resin down to the level of the upper surface of saidperipheral wall, to provide a unitary tile having a flat ornamentalupper surface constituting a central body bordered by a wide frame.

References Cited UNITED STATES PATENTS 2,179,289 11/1939 Galassi 94113,097,080 7/1963 Weir l179 3,174,977 3/1965 Hoiberg 943 3,194,856 7/1965Palmer 161162 X 3,238,682 3/1966 Tracy 523l1 X JOHN E. MURTAGH, PrimalyExaminer.

1. AN ORNAMENTAL TILE COMPRISING A SHALLOW OPEN TOPPED SHELL MEMBERINCLUDING A BOTTOM WALL AND AN UPWARDLY DIRECTED PERIPHERAL WALL, AMATRIX OF A SOLID SYNTHETIC ORGANIC POLYMER DISPOSED IN ANDSUBSTANTIALLY FILLING SAID SHELL AND ADHERING TO THE WALLS THEREOF ANDHAVING AN UPPER FACE, AND AN AGGREGATE MATERIAL DISTRIBUTED THROUGHOUTSAID MATRIX AND EXPOSED AT SAID MATRIX UPPER FACE, SAID PERIPHERAL WALLHAVING A WIDTH AT LEST SEVERAL TIMES GREATER THAN THE HEIGHT THEREOF ANDBENG MADE OF A MATERIAL CONTRASTING WITH SAID MATRIX AND SAID AGGREGATETO PROVIDE A COMPOSITE TILE HAVING AN ORNAMENTAL UPPER SURFACECONSTITUTING A CENTAL BODY BORDERED BY A WIDE, CONTRASTING FRAME.